Here, \(\Theta \)  denotes a hypocontinuous, bilinear map from \(O_M({\mathcal {L}}(X,Y))\times {\mathcal {S}}^{\prime }(X)\)  into \({\mathcal {S}}^{\prime }(Y)\)  (see the kernel theorem, e.g. in [1]}), and \(O_M({\mathcal {L}}(X,Y))\)  stands for the space of slowly increasing, smooth \({\mathcal {L}}(X,Y)\) -valued functions on \(\mathbb {R}\) .
